1. Technical Field of the Invention
The present invention relates to a printing method for block copy film and a block copy printer for preparing block copy film by performing monochrome print on transparent film.
2. Description of the Prior Art
As a conventional method for preparing block copy film, there has been adopted a method for printing desired monochrome printing information on transparent resin film as a printing medium in black ink using a normal heat transfer printer.
More specifically, the prior art, method in which a black ink ribbon and the transparent resin film are pinched between a thermal head mounted on a carriage of a heat transfer printer and a platen, the ink ribbon is unreeled while the thermal head is caused to reciprocate together with the carriage along the platen, and a plurality of exothermic elements formed on the thermal head are selectively electrically energized (for generating heat), based on desired monochrome printing information for recorded images, whereby black ink of the ink ribbon is partially transferred onto the transparent resin film for printing the desired recorded images and the like.
At that time, when printing of one print line is completed, there are repeatedly performed operations for conveying the transparent resin film by conveying means by the same length as the line-up length of the exothermic elements of the thermal head in a sub-scanning direction, and printing the next print line on a portion of the transparent resin film which is different from the portion printed until then, whereby the desired recorded images have been obtained as block copy film.
According to the aforesaid method, however, there have been clearances created in the joint portions between print lines, that is, between the lower end of a preceding print line and the upper end of the next print line, thereby generating white streaks under the conveying system of the transparent resin film in the sub-scanning direction. The trouble occurring between each print line is called xe2x80x9cstitchingxe2x80x9d is particularly conspicuous in monochrome block copy film. This consequently becomes problem and is a factor in determining whether or not it can be used as block copy film.
Also, in the finish in which the transparent resin film is coated in a single-layer state with ink, it has not been suitable for use as block copy film because of thin printing density.
The present invention has been achieved in the light of such problems, and is aimed to provide a printing method for block copy film and a block copy printer capable of adjusting printing density as occasion arises as well as making joints between print lines inconspicuous.
In order to accomplish the aforesaid object, a printing method for block copy film according to the present invention is, when performing monochrome printing based on printing data by selectively causing exothermic elements lined up and formed on a recording head to generate heat while a carriage is being moved along a platen for transferring black ink mounted on the carriage onto transparent resin film, and thereafter by repeatedly conveying the transparent resin film in a sub-scanning direction of the carriage, to set a predetermined mount of conveyance of the transparent resin film to 1/N (N is an integer of 2 or more) of a predetermined printing width, which is a line-up width of the exothermic elements, and to repeatedly print at a predetermined printing width after the transparent resin film is conveyed in the predetermined amount of conveyance.
By setting the amount of conveyance to less than the printing width in this manner, the upper end of each print line can be always located within the immediately preceding print line, and the problem on the stitching can be resolved.
Another printing method for block copy film according to the present invention is, when performing monochrome printing based on printing data by selectively causing exothermic elements lined up and formed on a recording head to generate heat while a carriage is being moved along a platen for transferring black ink mounted on the carriage onto transparent resin film, and thereafter by repeatedly conveying the transparent resin film in a sub-scanning direction of the carriage, to set a predetermined amount of conveyance of the transparent resin film to 1/N (N is an integer of 2 or more) of a printing width, which is a line-up width of the exothermic elements, at the commencement of printing, to print at a width obtained by substituting M=1 in M/N (M is an integer of 1 or more, M less than N) from the upper end of a predetermined printing width, and thereafter, repeatedly printing at a printing width obtained by adding 1 to the M of the immediately preceding printing width from the upper end until M=N is reached. Concerning print lines to follow, to repeatedly print at a predetermined printing width after the transparent resin film is conveyed at the predetermined amount of conveyance, and at the completion of printing, to print at a printing width obtained by setting M=N in the printing width from the lower end of the predetermined printing width and thereafter, repeatedly printing at a printing width obtained by deducting 1 from the M of the immediately preceding printing width from the lower end until M=1 is reached.
By adopting such structure, it is possible to obtain printing with uniform density by superimposing ink in N layers at any points within the printing area, and by setting the amount of conveyance to less than the printing width, the upper end of each print line is always located within the immediately preceding print line, whereby the problem of stitching can be resolved.
Further, a printing method for block copy film according to the present invention is characterized by the fact that, in a printing method for block copy film according to second means of the present invention, printing at the commencement and the completion of printing is performed respectively by either of the methods by control of repeating conveyance of a predetermined amount of the transparent resin film and selective heat generation of the exothermic elements, and control of repeating only selective heat generation of the exothermic elements without the transparent resin film being conveyed.
By adopting such structure, it is possible to superimpose the ink in N layers even at upper and lower end portions of a printing area, and to obtain printing at uniform density within the entire printing area.
A block copy printer according to the present invention is characterized by having: recording means having a carriage for reciprocating along a platen and a recording head which selectively causes exothermic elements lined up and formed to generate heat for transferring black ink mounted to the carriage onto transparent resin film; conveying means for conveying the transparent resin film in a sub-scanning direction of the carriage; and control means for determining a predetermined amount of conveyance of the transparent resin film to 1/N (N is an integer of 2 or more) of the printing width, which is a line-up width of the exothermic elements, based on the user""s desired recording density, and controlling to print at the predetermined printing width after the transparent resin film is conveyed at the predetermined amount of conveyance.
By adopting such structure, it is possible to always locate the upper end of each print line within the immediately preceding print line, thus making it possible to resolve the problem of stitching.
The block copy printer according to the present invention is characterized by the fact that, in a block copy printer according to the fourth means of the present invention, the control means controls so as to superimpose printing in the same number of times on the entire printing area of the transparent resin film. Also, the block copy printer according to the present invention is characterized by the fact that, in a block copy printer according to the fifth means of the present invention, the control means controls driving of the recording means and the conveying means in such a manner that at the commencement of printing, the printer prints at a width obtained by substituting M=1 in M/N (M is an integer of 1 or more, M less than N) from the upper end of the predetermined printing width, and thereafter, repeatedly prints at a printing width obtained by adding 1 to the aforesaid M of the immediately preceding printing width from the aforesaid upper end until M=N is reached, and at the completion of printing, prints at a printing width obtained by setting M=N in the aforesaid printing width from the lower end of the predetermined printing width and thereafter, repeatedly prints at the printing width obtained by deducting 1 from the aforesaid M of the immediately preceding printing width from the aforesaid lower end until M=1 is reached.
By adopting such structure, it is possible to obtain printing at uniform density by superimposing the same ink within the printing area.